Corrugated metal pipe

ABSTRACT

A metal pipe of single piece construction including a wall formed of a single corrugated metal sheet. The sheet has opposing first and second edges extending longitudinally along the sheet. The wall includes a seam that is formed by abutting portions of the first and second edges. The seam extends helically about and along a length of the wall. The sheet has an interior wall side and an opposing exterior wall side. The interior wall side defines an interior wall surface of the wall. The exterior wall side defines an exterior wall surface of the wall. The sheet has a sinusoidal cross-sectional profile defining 3 corrugation peaks at the interior wall surface and 3 corrugation peaks at the exterior wall surface. The sheet has a flattened sheet width of approximately 27 inches and a finished sheet width of approximately 21 inches. The wall defines a pipe diameter of at least 96 inches.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 13/325,848 entitled CORRUGATED METAL PIPE filed Dec. 14, 2011,the entirety of the disclosures of which are expressly incorporatedherein by reference.

STATEMENT RE: FEDERALLY SPONSORED RESEARCH/DEVELOPMENT

Not Applicable

BACKGROUND

The present invention relates in general to pipes, and moreparticularly, to corrugated metal pipes.

Corrugated metal pipe is used extensively in flood control, drainage andsewer systems because of its economic value, strength and durability.The pipe is usually fabricated in 20 foot and 24 foot sections; howeversections in other lengths are available. Widely used pipe diameters mayrange from 6 to as much as 300 inches and typical wall thicknesses are0.052 inches (18 gauge), 0.064 inches (16 gauge), 0.079 inches (14gauge), 0.109 inches (12 gauge), 0.138 inches (10 gauge) and 0.168inches (8 gauge).

Corrugated metal pipe derives most of its inherent strength from thecorrugations formed into the metal sheets or plates at the time offabrication. Helical corrugated pipe is a common type of corrugated pipewith helical corrugations, fabricated from corrugated metal sheet, witha continuous helical seam. Corrugated metal sheet is a mill product insheet or coil form for fabricating helical corrugated pipe products.Corrugations commonly used for metal pipes are circular arcs connectedby tangents, and are described by pitch and depth. Pitch is measured atright angles to the corrugations from crest (peak) to crest (peak) on asame side of a pipe sheet. Depth of a corrugation is measured from acrest of a corrugation to the lowest portion of an adjoining valley,both measured on a same side of a pipe sheet. A corrugation is namedusing its pitch and depth as “pitch by depth.”

A standard “3×1” helical corrugation profile features a 3 inch pitch anda 1 inch depth. Seven (7) corrugations are included on each side of themetal sheet. The corrugated metal sheet is formed from a flattened sheetwidth is about 27 inches (specifically 27¼ inches). The finished(corrugated) sheet width is 21″ (+−½ inch) with a lock seam. A standard“5×1” helical corrugation profile features a 5 inch pitch and a 1 inchdepth. Six (6) corrugations are included on each side of the metalsheet. The corrugated metal sheet is formed from a flattened sheet widthis about 34 inches (specifically 33 5/16 inches). The finished(corrugated) sheet width is 30″ (+−½ inch) with a lock seam. For largepipe diameters (over 48 inches), a 3×1 corrugation profile is theestablished industry profile. Traditional helical corrugated steel pipe(CSP) is limited to 144 inches in diameter to still meet the ASTM A796Structural guidelines for horizontal deployment.

Due to the structural limitations of typical helical corrugated pipe,for larger diameter vertical and horizontal pipes (such as 168-300inches) corrugated sectional steel plate is used. These largercorrugated metal pipes are typically used for vertical applications ascaissons and foundations for shafts, and for horizontal pipeapplications (such as in flood control, drainage and sewer systems). Inthis regard, a helical configuration is not used. Rather, individualsections of rectangular steel plate (of 120 inches by 72 inches) areeach formed to have lengthwise corrugations and the metal plates arecurved into widthwise arc segments. Multiple sections of metal plate arejoined together to form sections of pipe. The periphery of the platesections are punched to facilitate the plates being joined together.Typically, the steel plates are formed at a manufacturing plant and thenshipped to the installation worksite. At the worksite, the curvedsectional metal plates are delivered and then must be maneuvered to beassembled to form a pipe. This assembly process is a difficult processas the curved metal plates are cumbersome to maneuver by nature.

Accordingly, there exists a need in the art for an improved corrugatedpipe arrangement in comparison to the prior art.

BRIEF SUMMARY

According to an aspect of the present invention, there is provided ametal pipe of single piece construction including a wall formed of asingle corrugated metal sheet. The sheet has opposing first and secondedges extending longitudinally along the sheet. The wall includes a seamthat is formed by abutting portions of the first and second edges. Theseam extends helically about and along a length of the wall. The sheethas an interior wall side and an opposing exterior wall side. Theinterior wall side defines an interior wall surface of the wall. Theexterior wall side defines an exterior wall surface of the wall. Thesheet has a sinusoidal cross-sectional profile defining 3 corrugationpeaks at the interior wall surface and 3 corrugation peaks at theexterior wall surface. The sheet has a flattened sheet width ofapproximately 27 inches and a finished sheet width of approximately 21inches. The wall defines a pipe diameter of at least 96 inches.

According to various embodiments, the finished sheet width may bebetween 20¼ inches and 22⅛ inches. The seam may be a lock seam. Thesheet may have a corrugation pitch of approximately 7 inches. The sheetmay have a corrugation pitch between 6¾ inches and 7⅜ inches. The sheetmay have a corrugation depth between adjacent corrugations ofapproximately 2 inches. The wall may define a pipe diameter between 96inches and 288 inches. The wall may be cylindrical shaped. The metalsheet may have a thickness between 18 gauge and 8 gauge.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features and advantages of the various embodimentsdisclosed herein will be better understood with respect to the followingdescription and drawings, in which like numbers refer to like partsthroughout, and in which:

FIG. 1 is a cross sectional view of a corrugated metal sheet utilized inthe fabrication of corrugated metal pipe according to an aspect of theinvention;

FIG. 2 is a side view of a corrugated metal pipe in accordance with anaspect of the invention;

FIG. 3 is a cross sectional view as viewed from the axis 3-3 of FIG. 2;

FIG. 4 is an enlarged cross sectional view of a portion of a length ofcorrugated metal pipe constructed in accordance with an aspect of thepresent invention; and

FIG. 5 illustrates a section of corrugated metal pipe during fabricationfrom the corrugated metal sheet.

DETAILED DESCRIPTION

The detailed description set forth below in connection with the appendeddrawings is intended as a description of the presently preferredembodiment of the invention, and is not intended to represent the onlyform in which the present invention may be constructed or utilized.Reference throughout the detailed description to “one embodiment” or “anembodiment” means that a particular feature, structure, orcharacteristic described in connection with the embodiment is includedin at least one embodiment of the present invention. Thus, appearancesof the phrases “in one embodiment” or “in an embodiment” in variousplaces throughout this detailed description are not necessarily allreferring to the same embodiment. The following description is given byway of example, and not limitation. Given the above disclosure, oneskilled in the art could devise variations that are within the scope andspirit of the invention disclosed herein. Further, the various featuresof the embodiments disclosed herein can be used alone, or in varyingcombinations with each other and are not intended to be limited to thespecific combination described herein. Thus, the scope of the claims isnot to be limited by the illustrated embodiments. In the followingdescription, numerous specific details are shown to provide a thoroughunderstanding of embodiments of the invention. One skilled in therelevant art will recognize, however, that the invention may bepracticed without one or more of the specific details, or with othermethods, components, materials, etc. In other instances, well-knownstructures, materials, or operations are not shown or described to avoidobscuring aspects of the invention. It is further understood that theuse of relational terms such as first and second, and the like are usedsolely to distinguish one from another entity without necessarilyrequiring or implying any actual such relationship or order between suchentities.

Referring now to FIG. 1 there is depicted a cross sectional view of acorrugated metal sheet 10 utilized in the fabrication of corrugatedmetal pipe according to an aspect of the invention. The metal sheet 10includes three (3) corrugations 12 a-c on one side and three (3)corrugations 14 a-c on an opposing side. Each of the corrugations 12 a-crespectively includes corrugation peaks 16 a-c. Adjacent to each of thecorrugations 12 a-c respectively are corrugation valleys 18 a-c. Each ofthe corrugations 12 a-c respectively includes corrugation peaks 20 a-c.Adjacent to each of the corrugations 14 a-c respectively are corrugationvalleys 22 a-c.

The metal sheet 10 has first and second edges 24, 26. In the embodimentdepicted, each of the first and second edges 24, 26 are bent back uponthemselves in a lock seam configuration. The corrugation profile of themetal sheet 10 is characterized by a pitch (P) and a depth (D). Thecorrugated metal sheet 10 has a finished (corrugated) sheet width (W) ofapproximately 21 inches with a lock seam.

Referring now to FIG. 2 there is depicted a side view of a corrugatedmetal pipe 28 in accordance with an aspect of the invention. FIG. 3 is across sectional view as viewed from the axis 3-3 of FIG. 3. FIG. 4 is anenlarged cross sectional view of a portion of a length of the corrugatedmetal pipe 64 constructed in accordance with an aspect of the presentinvention. FIG. 5 illustrates a section of the corrugated metal pipe 28during fabrication from the corrugated metal sheet 10. As isillustrated, the metal sheet 10 may be “feed” towards the forming metalpipe 28.

According to an aspect of the invention, there is provided a metal pipe10 of single piece construction including the wall 32 formed of thesingle corrugated metal sheet 10. The sheet 10 has the opposing firstand second edges 24, 26 extending longitudinally along the sheet. Thewall includes a seam, such as lock seam 30, that is formed by abuttingportions of the first and second edges 24, 26. The seam 30 extendshelically about and along a length of the wall 32. The sheet 10 has aninterior wall side 34 and an opposing exterior wall side 36. Theinterior wall side 34 defines an interior wall surface 38 of the wall32. The exterior wall side 36 defines an exterior wall surface 40 of thewall 32. The sheet 10 has a sinusoidal cross-sectional profile defining3 corrugation peaks 20 a-c at the interior wall surface 38 and 3corrugation peaks 16 a-c at the exterior wall surface 40. The sheet 10has a flattened sheet width of approximately 27 inches and a finishedsheet width of approximately 21 inches. The wall defines a pipe diameterof at least 96 inches.

As mentioned above, the corrugated metal 10 sheet has a flattened sheetwidth of approximately 27 inches. As used herein approximately 27 inchesrefers to 27 inches +−manufacturing tolerances or specifications. Inthis regard, a ½ inch tolerance would result in approximately 27 inchesbeing used herein to mean be between 26½ inches and 27½ inches. Thecorrugated metal 10 sheet has a finished sheet width of approximately 21inches. As used herein approximately 21 inches refers to 21 inches +−manufacturing tolerances or specifications. In this regard, a ¾ inchlower tolerance and a 1⅛ inch upper tolerance would result inapproximately 21 inches being used herein to mean between 20¼ inches and22⅛ inches.

According to various embodiments, the metal sheet 10 may have acorrugation pitch (P) of approximately 7 inches. The metal sheet 10 mayhave a corrugation depth (D) between adjacent corrugations ofapproximately 2 inches. In this regard, in this embodiment, thecorrugation profile would be referred to as “7×2”. As used hereinapproximately 7 inches refers to 7 inches +− manufacturing tolerances orspecifications. In this regard, a ¼ inch lower tolerance and a ⅛ inchupper tolerance would result in approximately 21 inches being usedherein to mean between 6¾ inches and 7⅛ inches. The pitch would beimpacted based upon the specification for the desired flatten andfinished sheet widths and corrugation depth (D).

The wall 32 is defined by a longitudinal axis 42. The wall 32 defines apipe diameter (PD) with reference to the longitudinal axis 42. The pipediameter (PD) may be between 96 inches and 288 inches. In the embodimentillustrated, the metal pipe 28 is cylindrical shaped. The metal sheet 10may have a thickness between 18 gauge and 8 gauge. The metal utilized tofabricate the metal sheet 10 may be chosen from any of those which arewell known to one of ordinary skill in the art, such as steel. Further,the metal sheet 10 may be surface coated as may be desired.

The particular manufacturing processes for forming the metal sheet 10with the corrugation profile may be chosen from any of those processeswhich are well known to one of ordinary skill in the art. Moreover, theparticular manufacturing processes for forming the metal pipe 28 fromthe metal sheet 10 may be chosen from any of those processes which arewell known to one of ordinary skill in the art. While the seam 30 isdepicted as a lock seam, it is contemplated that other attachment orbonding arrangements, such as welding may be utilized, may be selectedfrom those which are well known to one of ordinary skill in the art.

It is contemplated that the structural strength of the metal pipe 28having corrugation pitch of approximately 7 inches and a finished sheetwidth of approximately 21 inches approximates that of a metal pipeformed of corrugated multi-sectional plate (with curved rectangularplates of 120 by 72 inches) of comparable gauge. As such, the use ofmultiple curved sectional steel plates to form corrugated pipe may beavoided in favor of the helical corrugated metal pipe 28 of the presentinvention.

Significantly, it is contemplated that helical corrugated metal pipefabrication equipment may be truck mounted and thus be considered mobilein nature. As such, helical corrugated metal pipe fabrication equipmentmay be utilized to form the metal pipe 28 at a worksite location. Metalsheeting may be provided as raw goods in the form of a continuous roll.

In contrast, the fabrication equipment used to produce metal platesections for corrugated metal pipe is not considered mobile. The processfor forming the curvature of the metal plates and corrugations for pipeapplications is one which requires heavy fabrication equipment. Othermanufacturing equipment is used for the punching processes used to punchholes in the periphery of the metal plates. Such equipment by nature isnot mobile and therefore would be only located and used in a fabricationplant. In this regard, use of metal plates for corrugated metal pipeapplications requires shipment of formed metal plates (widthwise curvedin to an arc segment, lengthwise corrugated, and perimeter punched) tothe worksite from the plate fabricator. Thus, use of metal sheets toform corrugated metal pipe at a worksite location avoids inefficienciesof shipment of curved metal plates in terms of cost, time and logistics.An additional benefit of helical corrugated pipe fabrication used at awork site is that the cumbersome process of joining multiple curvedmetal plates to form a metal pipe is avoided. Furthermore, use of theworksite fabricated helical corrugated metal pipe for large diameters(over 144 inches) is also comparatively beneficial in that a corrugatedpipe fabricator can stock just metal sheets with sheet widths ofapproximately 27 inch and still be able to produce corrugated metal pipein a full range of diameters, including beyond 144 inches, for bothhorizontal and vertical applications. This results in further economicefficiencies (reduced inventory costs by not having to stock metalplates) for the pipe fabricator.

What is claimed is:
 1. A metal pipe comprising: a wall formed of acorrugated metal sheet, the sheet having opposing first and second edgeregions extending longitudinally along the sheet, the wall including aseam formed by abutting portions of the first and second edge regions,the seam extending helically about and along a length of the wall, thesheet having an interior wall surface and an opposing exterior wallsurface, the sheet having a cross-sectional profile defining 3corrugation peaks at the interior wall surface and 3 corrugation peaksat the exterior wall surface, the sheet having a flattened sheet widthof approximately 27 inches and a finished sheet width of approximately21 inches.
 2. The metal pipe of claim 1 wherein the finished sheet widthis between 20¼ inches and 22⅛ inches.
 3. The metal pipe of claim 1wherein the seam is a lock seam.
 4. The metal pipe of claim 1 whereinthe sheet has a corrugation pitch of approximately 7 inches.
 5. Themetal pipe of claim 4 wherein the sheet has a corrugation pitch between6¾ inches and 7⅜ inches.
 6. The metal pipe of claim 1 wherein the sheethas a corrugation depth between adjacent corrugations of approximately 2inches.
 7. The metal pipe of claim 1 wherein the wall defines a pipediameter between 96 inches and 288 inches.
 8. The metal pipe of claim 1wherein the wall is cylindrical shaped.
 9. The metal pipe of claim 1wherein the metal sheet has a thickness between 18 gauge and 8 gauge.